"Hugo" <hua### [at] post3teledk> wrote in message
news:3c888cf0$1@news.povray.org...
> Hi,
>
> As suggested by Ron Parker, I'll report my observation here. My original
> post in the p.general group didn't give any feedback but maybe I didn't
> explain it so well.
>
> There's something strange with layered textures. I'll call it a flaw until
> someone convince me it's not. The way reflection is transmitted through
> layers doesn't work, with any POV version. Reflection is either
transmitted
> with full strength through all layers, or not at all.. Let me illustrate:
>
> camera { location -4*z look_at 0 }
> light_source { <-25,25,-25>, 1.5 }
>
> #declare Texture_1=texture {
>   pigment {rgb <1,1,1> }
>   finish { specular 1 reflection 1 }
> }
>
> #declare Texture_2=texture {
>   pigment { rgbt <0,0,1, 0.2> }
> }
>
> sphere { 0,1 texture { Texture_1 } texture { Texture_2 } }
> plane { 1*y,-2 pigment { checker rgb 1 rgb .5 } }
>
> As you will see, pigment and specular of Texture_1 is only 0.2 after
> Texture_2 has been added, but reflection still goes through the layer at
> full strength of 1.. I see no purpose in this behaviour. You can try to
> change the transmit value and see how the rest of the texture behaves in a
> different way as reflection.
>
> Best regards,
> Hugo
>

I played a bit with the settings. To me it looks like the final specular and
reflection values are the sum of those in the layered textures.

If you declare the two textures like this:
#declare Texture_1=texture {
  pigment {rgb <1,1,1> }
  finish { specular 0.5 reflection 0.5 }
}

#declare Texture_2=texture {
  pigment { rgbt <0,0,1, 0.2> }
  finish { specular 0.5 reflection 0.5 }
}

the resulting image looks the same as that of your test scene. (actually
there is a slight difference, especially in the specular reflection)

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